Loch Castle, Medieval castle in Nittendorf, Germany.

Loch Castle is a castle in Nittendorf built into natural rock, containing two large caves sealed with thick stone walls. These chambers connect through a network of passages, while the tower restored in 1989 rises 22 meters with walls that decrease from two meters thick at the base to 50 centimeters at the top.

The founding date is not certain; historians consider either the 12th or the 14th century. The Rammelsteins, ministeriales of the burgraves of Regensburg, built it to guard a hammer mill and to watch the Schwarze Laber valley. In 1556 the last male Rammelstein died and an inheritance dispute followed, settled in 1573 in favour of the Sauerzapfs. By 1625 Veit Philipp Sauerzapf had moved to Schönhofen and the castle stood empty.

The name 'vom Loch' appears in a 1380 document, when Jakob Rammelsteiner used it as a surname addition. The castle guarded a hammer mill and watched over the Schwarzen Laber valley, and it may have stored goods from the Loch hammer mill. Visitors can still see the fireplace in the largest cave room.

The ruin is freely accessible but has no facilities or marked paths; the collapsed ceiling of the main cave lets you enter from both the hillside and the valley side. Sturdy shoes are advised, and a torch helps in the smaller cave chambers. The round bergfried is the only intact structure and is visible from afar.

The round bergfried in front of the cave is the only intact structure left, about 22 metres high with two-metre-thick walls at its base. It held a garderobe whose medieval wooden seat is still preserved, and it was restored in 1989.